Technical Field of the Invention
Implementations consistent with the principles of the invention generally relate to the field of integrating optical sources into semi-conductor based point-of-care medical diagnostic and test equipment, more specifically to systems and methods for integrating optical sources in neural probes.
Background
Timely medical diagnosis historically has been hampered by the limited ability of medical professionals to conduct various medical tests at the point of care. Patients often have visited their doctor, only to be sent to a separate lab facility to have blood work or other diagnostic tests conducted. Diagnosis of the patient was then delayed to wait for the lab results to be returned to the doctor for an informed diagnosis of the patient's condition. The size, cost, complexity, and diversity of medical test equipment needed to properly diagnose the full range of medical conditions to which the medical professional may be exposed has limited the amount of point of care diagnostic equipment available to the typical medical professional.
Thus there is a need in the art for cost effective point of care medical diagnostic systems that can be used by the typical medical professional.
Certain medical diagnostic devices require a light source to conduct their tests. Example devices include pulse oximeters, flow cytometers, DNA sequencers, and immunoassays. A pulse oximeter is a clinical device that uses the differential absorption of visible (red) and infrared light by hemoglobin to detect changes in blood oxygenation. A flow cytometer uses scattering or other optical information from fluorescently-labeled cells to count and otherwise quantify the type and quantity of cells in a sample. DNA sequencing relies on a variety of analytical and chemical techniques, however the detection of processed DNA strands is often accomplished with a fluorescent or other optical signal. Finally, an immunoassay uses the competitive binding of an antibody to detect the concentration of an analyte of interest in a sample. Detection of the antibody/antigen binding can be done in a variety of ways, but is often accomplished with optical methods such as fluorescent detection. Typically the light sources utilized in these and other similar devices have led to large, cumbersome test devices to connect the light source, power source, control electronics, and other data or sample collecting sensors. This size and complexity has added to the expense of these diagnostic devices and limited their use at point of care.
There is thus a need in the art to integrate optics into portable point of care medical diagnostic devices to reduce the cost, size and complexity of such devices.
In addition, certain test devices must be implanted into a test subject to collect data. Neural probes are one such example. For example, it is known by those of skill in the art that directing light to a very localized and precise region of excitable neural tissue can be used to open ion channels that were previously implanted into the neural cells with genetic techniques, causing those channels to open and thus an action potential to fire. An action potential is a stereotyped voltage waveform that arises from ionic current across a cell membrane.
Various designs of neural probes have been attempted in the art to use these phenomena for test purposes. For example, silicon neural probes with an optical fiber glued to it in order to direct light to the very localized and precise region of excitable neural tissue have been attempted. Metal recording sites on the neural probe detected the electrical cell activity of the optically-triggered action potential. These devices required an external optical source and were extremely tedious to assemble and were thus expensive and demanding to build and operate. These shortcomings place such method and devices beyond the reach of most researchers of clinicians.
Some recent efforts at integrating the light delivery with the microelectrode have been reported, however these approaches rely on highly labor-intensive “one-off” assembly procedures in which optical fibers are etched and then manually aligned and attached to silicon recording arrays. Other groups have demonstrated probes with integrated waveguides, however the light sources (i.e. laser or LED) are bulky and are separate from the probe and connected by a fiber which is problematic for behavioral experiments.
There is a need in the art for a neural probe with integrated optical stimulation that allows implanting the probes without a tether, and enables the selective stimulation and monitoring of neuronal activity in freely behaving animals.
There further is a need in the art for a neural probe with an integral optical source to simplify the performance of experiments in which it is desired to optically stimulate a targeted set of neurons while accurately recording responses from those and other neurons.
There further is a need in the art to integrate one or more optical sources in a neural probe to facilitate implanting the neural probe in an animal or human test subject.